1. Field of the Invention
The present invention relates to a working machine having an internal combustion engine mounted in a casing also known as self powered machines or tools, and more particularly, to a working machine in which a carburetor is supported on a casing in a vibration preventing manner.
2. Description of the Related Art
In working machines such as chain saws on which a small two-cycle internal combustion engine, for example, is mounted, a carburetor is conventionally coupled with and secured to a casing including the internal combustion engine through bolts, or the like.
With this conventional mounting arrangement, the vibration caused on the casing by the operation of the internal combustion engine is directly transmitted to the carburetor, thereby a problem arises in that an air-fuel mixture is unstably supplied to the internal combustion engine by the carburetor and that the carburetor is liable to be broken.
To cope with this problem, it is preferable that the carburetor be supported on the casing in a vibration preventing manner. In this case, however, it is preferable to further satisfy the requirements for reasonably arranging the structure of the carburetor in a compact size.
Accordingly, it is an object of the present invention, which was made in view of the foregoing circumstances, to provide a working machine having an internal combustion engine in which the carburetor has excellent vibration isolating properties on a casing and has a reasonable and compact structure.
To achieve the above object, in a working machine according to the present invention, a portion of the air-fuel mixture discharging port of a carburetor is supported on a casing through a first vibration preventing member. In addition, the adjustment screws of the carburetor are supported on the casing through a second vibration preventing member.
According to the present invention, the carburetor is supported on the casing by the air-fuel mixture discharging port and the portion of the adjustment screws. Then, the first vibration preventing member is interposed between the casing and the air-fuel mixture discharging port, and the second vibration preventing member is interposed between the casing and the adjustment screws, thereby the direct transmission of the vibration on the casing to the carburetor side can be prevented. Further, a reasonable and compact carburetor support structure can be provided because the air-fuel mixture discharging port and the adjustment screws for supporting the carburetor on the casing are intrinsically provided with the carburetor itself.
In a preferred embodiment of the present invention, the first vibration isolating member may be interposed between the air-fuel mixture discharging port and the casing to cover the outward projections that are formed to the air-fuel mixture discharging port so as to extend outward in the diameter direction of the opening of the air-fuel mixture discharging port. This arrangement is preferable because the supporting stability of the carburetor with respect to the casing side can be improved thereby.
As another embodiment of the present invention, the second vibration isolating member may act also as a seal member for sealing the outside of a carburetor chamber for accommodating the carburetor from the inside thereof in a dustproof manner. This arrangement is more preferable because the dustproof property of the carburetor chamber can be improved thereby.
As still another embodiment of the present invention, the second vibration isolating member may have guides for guiding a screw driver for rotating the adjustment screws to the heads of the adjustment screws. This arrangement is further more preferable because the screw driver securely reaches the heads of the adjustment screws by being guided by the guides and thus the adjustment screws can be smoothly and promptly rotated.